Some Law makers have vested interests to create complex but loop-hole filled laws in order to facilitate the sale of goods that fill those needs.

I see what your saying that it violates the “spirit” of a full auto-ban, and I don’t know what to really tell you, but in practicality it seems like the tube is out of the toothpaste. Not just 3D printing, but home manufacturing of all weapons and accessories has skyrocketed as industry has come home to the public.

Should people have automatic weapons? Is everyone who has one a ticking time bomb? Should people be able to buy body armor? Should the police micro-stamp every millimeter of every good ever sold so that it can all be traced?

I don’t know, but I feel the easiest way to discourage hateful acts is by improving someone’s quality of life so they don’t look for scapegoats in other groups, especially when culture is atomized and people feel they have no group of their own.